Machine for grinding internal surfaces of workpieces



June 1, 1948. Q E, FRUNK 2,442,595

MACHINE FOR GRINDING INTERNAL SURFACES OF WORKPIECES- Filed April 16, 1945 2 Sheets-Sheet 1 IZn Ven 2 02 0. E. ffiu/wr.

Patented June 1 1948 -Application April '16, 1945,?Smi9jl'No. 588 382 *In Sweden Mareh?13,?1:944

Claims. 1

The present inuentionsrefers to .a method of grinding, particularly of internal surfaces-bore :ho'les andithe like in work :pieces havinga rotary movement .and a simultaneous reciprocating (movement imparted thereto, the @latter :movement being performed in :the axial direction of two coaxially mounted. rotating grinding tools. 'In grinding machinesof this kind, the work piece iscgenerally arranged .in ;a holder, which may-be swung iinza plane at right angles to the grinding spindles, in order to render possible insertion zandxemoval .and controlling measurement of the work "piece. "130 permit this oscillatory movement of the "holder, the grinding tools would zhitherto "be generally arranged at so great a mutual distance on both sides of said holder that :the-rwork :piece or the holder thereof might be moved intoand out of operative position without being prevented therefrom by the grinding tools. This'arrangement of the grinding tools vatra relativelygreat mutual distance su'fiersi-rom the drawback that :the grinding-tools will leave :the grinding surface :for each stroke of the'work piece during the reciprocating movement of the work piece, and-will again be moved in onto the same when the direction-of movement is reversed. lt -has been found thata borehole ground in this waywill not become exactly cylindrical, but :ob'ta'ins atthe endsthereof a somewhat larger diameter than the remainder of the bore hole. The reason of this is the inconsiderable :resiliency of "thegrin'ding spindle caused-by the pressureof the grinding tool on the'grinding surface, said'resiliency involving 'a certain even if immaterial deviation of the -grinding tools from the centered positiontaken bythe same in their unloaded state. The present invention has for its object to obviate this disadvantage, .iandprin- "(finally consists 'in that the grinding tools are adjusted, prior-to the grinding operation, in the axial direction relatively to each other so as "to be'located-at *a mutual distance which is smaller than the length 'of *the surface to "be ground, whereupon the -=worl piece will have mparted thereto'a'reciprocatingfmovementlimited in such manner "that t-he grinding-tool does not'leave the grinding :surface altogether during the grinding operation. For example, if -a througlibore in a work piece is-to he "ground along :the whole of its length, *the grinding tools are adjusted to a mutual distance, which "is -zwproxlmately equal {to or "smaller than half'the length of .the bore. Toifaeilitatezsuch axial adjustment of fthe grindlug-tools, the grinding spindlelhousings,

.displaceable-aoeording ,to the invention, -i-n guiding hearings of the machine :fram-e while "being provided with clutching means, :by "which the grinding spindle housings :may 'be locked in every position :of adjustment. It is important thereif ore, that the clutching zineans :beconstructed in such :manner that :the loosening andzsecuring .of the :spi-ndlehousings does notiinvolve any displacement ofuthe coaxialpositiomof the grinding spindles. vthist-end eachspindle housing is provided, iaceordmg 3-150 the invention, with two clamping devices arranged to effect clamping of .the pindle .housingeinitsqguiding :bearing and to .be actuated by a common tightening contrivance which is so arranged :and balanced that the tightening power will bewqually distributed on both clamping devices. Preferably, the two clamping devices :are for this purpose adapted to be actuated .hy means wot :a leverage comprising .two levers connected vat vthe :ends thereof with the clam-ping members :of thetwo clamping devices, said levers fleeing actuatedat the centre thereof by the :commonotightening .cont-rivance, so @that the tightening power is distributed through the zkevers :to-tthe same extent onto :the two clamping devices.

Fllheinvention she-described more closely with "reference "to 'tthe accompanying drawings, which illustrate a :form 10f embodiment of a 'grindingzmachine constructed inaccor'dance with the invention. "1 a plan view' showing the most importanttparts. of'the machine. Fig- '2 :is sans-axial ':section-through the bearing housing for a'rotating chuck. :Figure3 isa cross section vziilsn'ough the tclutching means f or one of athegrinding spindle rhousi-ngs. :Figure 4 shows :the clutching means viewed in elevation, and :EignrerS isxatplan v-iew of the upper :part-o'f the clutching means.

The machine is provided with two grinding spindles :l, 2 z-ca rying-nt-the rree ends thereof a grinding roller -3 sand respectively,- said spindles iheing mounted in cylindrical gri-nding spindle :housings and 'displaceab'le in-guiding bearings .zarranged 11in braekets 1 "and 8, respectively, which are rigidly connected with 'the mac'hine :frame, only a portion *9 ef which is shown in Figure .1. The Blatter :part with the"brackets' 1, 8 and the grinding spindle housings arranged thereon :is tgdisplaceahle:0n:=guides in :a direction perpendicular -torthei rinding :spindle axis. ".The grinding :spindles, as well as the appertaining grinding spindle housings are :eonieally arranged iinlathaelyrto each 1.0111191 land displainable in ivthe the grinding spindles are mounted. areaxially axial-direction was is l nem m 'i ezsr s extreme end of. the spindle housings, said turbines being driven by means of compressed air supplied through passages in the machine frame and through flexible tubes l2, l3. The axial ad justment of the grinding spindle-housings is effected with the aid of handles l4, -l5 in the form of double-armed levers, which are mounted in arms l6, l1 projecting from thbrackets 1, 8,

and which are coupled tothe grinding spindle housing by means of bifurcated members not visible in the drawings, said. members grasping about flanges l8, IS on the turbine casings. For the purpose of effecting an accurate axial adjust ment of the grinding spindles in the operative position, there are provided stop screws 20, 2|, which are screwed through threaded holes in the flanges l8, l9, and which, when the grinding spindles are adjusted inwardly, are caused to bear with their ends on abutting surfaces on the brackets 1, 8. During the adjustment of the grinding spindles, the grinding spindle housings may move freely in the respective recesses in the brackets '1, 8. After the adjustment has been eifected, the grinding spindle housings are each locked by means of a clutching device, the construction of which will appear more closely from Figures 35.

The grinding spindle housing 6 is displaceably mounted in a bore in the bracket 8, wherein it is fitted as accurately as'possible, and is adapted to be locked in the position of adjustment by means of two'similarly constructed clamping devices arranged at a suitable axial distance from each other. In the example shown, each of these clamping devices consists of a piston 23 displaceable in a bore 22 and of a sleeve 24, which is likewise displaceable in the same bore, said piston and sleeve being bevelled oif at the end portions thereof bearing on the spindle housing, so as to form a uniform-bearing surface in these places against the wall of the spindle housing projecting into the boreZZ. The piston 23 is provided with apulling rod 25 extending through the sleeve 24, said rod being drawn through apertures in two levers or yokes 26, .27 and being provided at the upper end thereof with nuts 28 threaded thereon, said nuts bearing against the upperside of the yoke 21; The lower yoke 26 bears on the end 29 of the sleeve 24 projecting over the bracket. The upper yoke 21 is provided at the centre thereof with a threaded bore having a clamping screw 30 screwed into the same, said clamping screw abutting with its lower end against the upper side of the lower yoke 26-. and being provided with a head Si and a handle 32 connected thereto, by means of which the clamping screw may be turned to tighten up the two clamping devices. By the turning of the screw 30 by means of the handle 32,- the two yokes are pulled apart while exerting a downward pressure on the sleeves 24' and an upward pull on the rods 25,- so that the two clamping members 23,- 24 are set'against the spindle housing so as'torigidly'lock the same in its position of adjustment. Through the arrangement described of the two yokes and the tightening means 30, 3|,32, the tightening power is distributed equally on the two clamping devices, in a manner such that every oblique positioning .of the grindinglsp'in'dle housing'in its guiding bearings is prevented. Since the two clutching devices are of the same construction and arrangement relatively to the respective grinding spindle housings 5, 6, safety is ensured for non-displacement of the coaxial position of the grinding spindles. As a further measure of safety for this purpose, there are provided stop abutments in the form of pins 33 on the upper yokes 21, in such manner that the magnitude of the tightening power is limited and may be kept as far aspossible equal on the two grinding spindle housings.

'As will appear from Figure 2, the work piece inthe example shown consists of a sleeve 34 provided with a through-bore intended to be ground on the inside-thereof. The work piece is intended to be fixed in a coaxial position within a work piece is effected by means of a slitted sleeve .52 in the Wall of the holder.

42, which is moved in between a cylindrical portion of the Work piece and a conical portion of the chuck by means of a sleeve 43 threaded into the chuck 35. The interior of the bearing housing is covered outwardly by the annular. plate 40, on the one hand, and, on the other hand. by a plate 44 screwed fast into the chuck 35.

The chuck 35 is adapted to be driven from a motor, not illustrated in the drawing, through the agency of a belt 45, which is laid into a belt groove 46 in the chuck, and Which is driven from a pulley 41 which, in turn, is coupled to the motor through a worm wheel 48 and a worm 49, the shaft of which is extended through a slit 5!] in the wall of the hollow holder 31. The holder 3'! is swingably mounted in a pin 51, on the one hand, and, on the other hand, in a pin coaxial therewith on a journal not illustrated in the drawing, said journal fitting into a through-hole The pulley 41 and the worm wheel 48 are arranged on a shaft mounted within theholder 3?,said shaft being coaxial with the oscillatory axis of the holder. Thanks to the swingable arrangement of the holder 3?, the bearing head with the workpiece arrangedtherein may be swung into and out of the working position shown in Figure 1. When the work piece is to be subjected to a controlling measurement, or is to be removed, the holder 37 is swung round by At the same time, an adjusting tool in the form of a grinding diamond arranged on the holder is brought into working position to turn down the cylindrical Working surfaces of the grinding rollers.

As will be seen from Figure 1, the motiontransmitting means between the rotating chuck '35 and the appertaining driving motor is :entirely encased within the holder 31 and the bearing head 36 connected thereto. To close the "slit 50, through which the motor shaft is extended, there is provided a ring 54 on the outside of the holder in a position coaxial relatively to the turning-axis of the holder, the motor shaft then extending through a hole in said ring, which consequently does not participate in the oscillatory movement of the holder 37. The holder 31 and the driv ing motor, are arrangedincommonon --a slide or the like not shown in the drawing, .said slide having a, reciprocating movement imparted thereto by means of motive'power, inYa direction paralleling the grinding spindles. Before the grinding operation is commenced,

the grinding rollers 3, 4 are adjusted by means of the handles l4, l5 and the screws 20, 2| into a working position relatively to each other adapted to the work piece in consideration, whereupon the grinding spindles and the grinding disks are turned down by means of the dia mond 53. After that, the grinding spindles are moved apart by means of the handles l4, 15, the holder 31 with the work piece inserted therein being turned down into its working position, in which the holder bears on an abutment on the frame of the machine. Then the grinding disks are introduced by means of the handles l4, l5 into the bores in the work piece, so as to take the previously adjusted position. The grinding rollers are then caused to bear on the insides of the bores by the frame part carrying the brackets 1, 8 being displaced in its guides at right angles to the axial direction of the grinding spindles. The grinding process is per-formed in known manner by a reciprocating movement being imparted to the holder 31, said movement taking place in the axial direction of the grinding spindles, According to the invention, the grinding rollers should be so adjusted relatively to each other that none of them leaves the grinding surface during the grinding operation but is always kept in contact with the latter. To this end, the grinding rollers should be so adjusted as to come on a mutual distance which, counted between the end surfaces of the rollers facing one another, or between the centre points of the rollers, is equal to or smaller than half the length of the bore hole to be ground.

I claim:

1. A grinding machine, particularly a machine for grinding internal surfaces of work pieces. comprising two coaxially mounted rotating grinding tools operating upon a single uninterrupted surface of the work piece and relatively spaced a distance apart which is smaller than the length of the surface to be ground, two grinding spindles carrying the two grinding tools and coaxially mounted in cylindrical bearing housings, and a holder for the work piece swingably arranged between the grinding spindle housings, which latter are axially displaceable in guiding bearings in the machine frame and provided with clutching means by which the grinding spindle housing may be locked in every position of adjustment, each spindle housing being provided with two clamping devices adapted to effect clamping of the spindle housing in its guiding bearings and to be actuated by a common tightening contrivance which is so arranged that the tightening power will be equally distributed on both clamping devices.

2. A grinding machine according to claim 1, the two clamping devices being adapted to be actuated by means of a leverage comprising two levers connected each at the end thereof with a clamping member in the respective clamping device, said levers being adapted to be actuated at the center by means of a common tightening contrivance so that the tightening power is distributed through the levers equally on the two clamping devices.

3. A grinding machine according to claim 1, the clutching means of the two spindle housings being of the same construction and arrangement relatively to the respective grinding spindle housings in order that the spindles shall always maintaln their coaxial position.

4. A grinding machine according to claim 1, the swingable holder for the work piece consisting of a closed hollow body containing the motion transmitting members through which the motion is transmitted from a driving motor to the rotating chuck or the like in which the work piece is to be secured.

5. A grinding machine according to claim 1, the swingable holder for the work piece consisting of a closed hollow body containing the motion transmitting members through which the motion is transmitted from a driving motor to the rotating chuck or the like in which the work piece is to be secured, the motion transmitting members comprising a belt running on the one hand over the chuck and on the other hand over a pulley which is preferably coaxially arranged relatively to the oscillatory axis of the holder.

" OTTO EMANUEL FRUNK.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,036,543 Bath Aug. 27, 1912 1,624,211 Bryant Apr. 12, 1927 2,149,519 Frunk et al. Mar. '7, 1939 

